Building Materials and Composites Lecture Notes - Week 8 Lec 36-40 PDF

EL P Building Materials and Composites T N Dr. Sumana Gupta Department of Architecture & Regional Planning, IIT Kharagpur Module 08 : Paints and Plastics Lecture 01 : Paints ...

EL P Building Materials and Composites T N Dr. Sumana Gupta Department of Architecture & Regional Planning, IIT Kharagpur Module 08 : Paints and Plastics Lecture 01 : Paints CONCEPTS COVERED EL T What is paint P Purpose of paint N Characteristics of good paint Composition and function of ingredients Steps for manufacturing of paint  What is paint A paint is a solution or suspension which after application to a substrate in a thin layer, converts to a solid film. Substrate may be wood, metal, plastered wall, concrete How thick or thin is the layer/ film? 60 -150 micron EL P How many layers are usually applied? At least two and up to four T Why multiple layers? N To hide surface imperfections How much can one liter paint cover? Usually 10 – 12 sqm, but depends on other factors  Purpose of paint Provides a coating to the building surface for protection against Weathering action of sun and rain, makes surface waterproof Mechanical stresses L Chemical actions like corrosion of metals, alkali reaction E Protects all surfaces against organic growths, termites, fungal attacks like wood or brick P T Provides aesthetic value/ identity to the building surface applied – both interior or exterior N Paint increases the surface durability and also can give fire protection Adds functionality modifies light reflection or heat radiation of a surface Paints help to identify hazards or to identify the functions of equipment and pipelines. Oxygen pipe line in Hospitals, A/C ducts, Fire service lines, oil and other gas lines in factories Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com  Characteristics of good paint Uniform spread- even texture/ colour of the paint L High surface coverage- lesser use of material and thinner coat E Good workability – workman can draw it easily on surface Durability – long lasting T Elastic property to stand weathering- comes out in patches from surface P Impervious to air and water- no visible break in paint layer N Cheap and economical- easy to procure and protect surface  Composition of paint Base Comprises of ‘Principal’ and ‘Pigment’ Dry component Base is generally held in suspension rather than solution L When paint is left to stand too long the pigment settles down. Needs stirring. E Base forms body of paint makes the paints film hard, strong, elastic Base T Vehicle Saves surface against cracking, moisture and UV rays. P Presently in use: zinc oxide, zinc carbonate, iron oxide, titanium oxide N Pigment are colouring agent usually mineral powders or organic substances Dimension – 0.1 to 5 µ meter in diameter Pigment hides surface imperfections Fineness of pigment reinforces the paint film They can give resistance to fire Prevents chemical action Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com  Composition of paint Vehicle – Binder and Thinner Binder binds the base (Principal and pigments) together to form a L continuous hard film. E When the paint dries the vehicle evaporates and binds the base particles to surface together. P T Glue size or linseed oil, synthetic resins such as alkyd, acrylic, vinyl or polyurethane N Thinner (solvent / carrier) added to get desired consistency for working and getting uniform coverage. Solvents may be Volatile Organic Compounds that get released into the air as the paint dries. Mineral solvent – Petroleum, spirit, Naptha, Turpintine, water  Composition of paint Additives Adulterant added to paints to increase its bulk volume without effecting its L useful properties. Inert towards other components. Chalk, gypsum, barite or barium sulfate (BaSO4), silica and magnesium silicate. Drier or plasticizer T E P helps in oxidation process or condensation process of the vehicle. N Up to 3% by weight can be added. Excess will help paint to flake out. modifies surface tension improves flow properties improves finished appearance improves pigment stability  Manufacturing of paint Step 1 – Mixing of the basic ingredients in mixer in desired amounts EL Step 2 - Grinding the ingredients in grinder for desired fineness T Step 3 - Thinning with solvent to desired consistency N P Step 4 - Agitating mix to avoid segregation Step 5 – Packaging on order  EL PT N  EL P Building Materials and Composites T N Dr. Sumana Gupta Department of Architecture & Regional Planning, IIT Kharagpur Module 08 : Paints and Plastics Lecture 02 : Paints (continued) CONCEPTS COVERED EL T How does paint work? Calculating CPVC N P Defects of paints  How does paint work? Pigment Volume Concentration – PVC Defined as the ratio of the volume of the pigment divided by the volume of L both pigment and binder together. E Expressed in percentage. Solvents and other materials are volatile and not present in the dried film T Hence it is not included in the denominator. P PVC = Pigment Volume / (Pigment Volume + Binder Volume) N Wetting - the phenomena of surrounding every pigment by sufficient binder as a protective coating. There should be sufficient binder to fill in voids between pigment particles. The consistency at which it is reached is called CPVC or Critical Pigment Volume Concentration  How does paint work? PVC value is below the CPVC - A solution qualifies to be called paint. Factors controlled by PVC Hiding power or opacity L Glossiness of paint E Permeability T Adhesion Washability P Durability N Pigments with platelet shaped particles like mica or aluminum can reduce permeability especially if they are aligned parallel to the coating surface. Increasing PVC reduces gloss and makes paint flat (50 -75%) Moderate value of PVC makes semi gloss paint (35 – 40%) Decreasing PVC has more of binder and is glossier (25 – 30%)  Calculating CPVC CPVC = 1/1+(Oil Absorption) x p /93.5 93.5 = 100 times Density of linseed oil (0.935) EL If binder is water density is 1 (divided by 100) T Oil Absorption (OA) = Grams of linseed oil/100grams of pigment N P p = Density of the pigment in gm/cc Say OA = 20, p =4.2; CPVC = 0.5269 i.e. 52.69% Maximum OA = 25 Increase in density (p) decreases CPVC. So denser the base, lesser is the CPVC.  Defects of paints Paints can be applied on wall surface (plastered) wood surface L metallic surface E concrete surface T Un-uniform paint P Both Old and New surface N Defects Quality of ingredients Workmanship defects Improper surface treatment Peeling of paint  Defects of paints Quality of ingredients L Chalking Mildew Chalking – less of vehicle (oil) in the coat E Grinning – insufficient opacity exposing the substrate Blooming – defect of paint or improper ventilation T Fading or discolouration due to atmospheric agents P Mildew due to fungal growth N Saponification due to chemical action like alkalies Flashing or glossy patches due to bad quality paint  Defects of paints Workmanship defects Running and sagging of paint L Brush marks Wrinkling due to thick layer of paint application E Aligatoring fine cracks due to different types of paint T N P Improper surface treatment – leads to lack of adherence Blistering and peeling – trapped air bubble under paint film or grease on substrate Flaking – lack of bonding between two layers of paint or paint and substrate  EL PT N  EL P Building Materials and Composites T N Dr. Sumana Gupta Department of Architecture & Regional Planning, IIT Kharagpur Module 08 : Paints and Plastics Lecture 03 : Paints (continued) CONCEPTS COVERED EL T Types of paints P Application of paint N Special paints Nano application in paints  Types of paints Paints Interior Exterior L Wood Metal Distemper Plastic Emulsion PU & Melamine Varnish T E General purpose enamel Cement paint P Dry Regular Synthetic Enamel Acrylic emulsion Synthetic Economy Premier Enamel Textured plastic N Acrylic Silk Apply paint only when the surface is dry Primer coat - an initial coating. Priming ensures better adhesion of paint to the surface, increases durability, and protects material being painted. Wall Putty – Sublayer acting as sealant or filler. Hydroxy Propyl Methyl Cellulose a gelatinous substance or cement based powder  Interior Paints Distemper – most common paint used for interior walls and ceilings Water based, washable, durable and smooth Dry distemper – available dry and has to be mixed with glue and water L Acrylic distemper has acrylic co-polymer formulation. It is water-based paint and provides smooth surfaces. T E Synthetic distemper or Oil bound distemper is a paint that includes drying oils that increase coverage area. Paint film gets harder with time making the surface easy to clean. P Plastic emulsion paint is water based wall paint. It consists of tiny polymer particles emulsified in water within which the pigments are trapped. High spread (15m2/lt) N The paint dries and the particles fuse together creating a film of paint on the wall. ease of application quick drying properties no bad odour washable scratch resistance anti-fading  Exterior paints Cement based paint - water based exterior paint with cement as base Weather proof Blocks Ultra Violet Radiation L Best adheres on newly plastered wall E Textured paint - Water reducible paint T Cement is the base and also consist of coarse grains like gypsum, sand and metal with binder used for creating a rough pattern effect on a wall. P Popular trend in external painting as different types of styles can be created on the wall surface. Provides better protection of exterior wall in acrylic polymer emulsion. N Acrylic paint - is a fast-drying paint made of pigment suspended Acrylic paints are water-soluble, but become water-resistant when dry. Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com  Wood and metal paints Varnish is a solution of resin or resinous substance like amber, copal, shellac etc. in alcohol, turpentine or spirit. Varnish is primarily used as wood finishing applications where the natural fibers and grains in the wood are intended to be visible. Polyurethane or melamine coating EL It is synthetic hydrocarbon polymers which form a film over the wood surface. T Can protect the base material from corrosion, weathering, abrasion to some extent. Drawback: Laminates wood and makes wood unbreathable. Metal surface N P Enamel paints are oil-based paints. Cheap, durable and water proof. It is anti termite and hence can be applied on wooden surface also. The oil content allows the paint to mix and go on smoother and adhere to surfaces longer  Application of paint For plastered / concrete wall (New surface) Free alkalis in hydrated cement remain on wet surface which leads to flaking of paint layer. Paint to be applied on dry surface. L Zinc Sulphate may be applied in wet weather condition to free off the alkalis on wall surface. E A layer of glue may be applied on surface to reduce consumption of paint, achieves economy. Damped surface needs an initial coat of paraffin, benzolene and resin in 5:4:3 For old wall surface P T N Old paint to be removed Surface to be freed from efflorescence, chalking, glossy patches, organic growth washed and dried cracks if any to be filled in before applying paint  Application of paint For metal surface L Clean surface with stiff brush or emery paper to free from rust E Metal hydroxides/ oxides do not provide a solid surface T for the paint to adhere to- paint flakes off. P Grease removal - with petroleum or alkaline solution like N Sodium bicarbonate, Sodium hydroxide Primers have high adhesion and chemical-resistance properties of the binder and anodic metal oxide as base (ZnO)  Application of paint New Wood surface Dry, clean, seasoned wood Knots to be filled in with hot lime - resins from wood cannot come out and damage finish L Application of primer to fill in pores E Usually varnish or melamine coat is applied in three layers after subsequent drying T Old wood surface P The earlier coat needs to be removed by sand paper etc Any oily or greasy substance to be washed by soap water. N New coats of paint to be applied on dry surface Thixotrophy – time dependent sheer thinning property of gels and fluids Fluids thick and viscous under static condition flows over when shaken  Special paints Aluminum paint - Very finely ground aluminum is suspended in either quick drying spirit varnish or slow-drying oil varnish. L Anti corrosive paint - A pigment such as chromium oxide, lead, red lead or zinc chrome is taken and after mixing it with some quantity of very fine sand, it is added to the paint. T E Asbestos paint - Asbestos fibres added in paint. Applied on the surfaces P which are exposed to acidic gases and steam. Also used as fire proof paint. Similar to lead asbestos is also unhealthy. N Bituminous paint - is prepared by dissolving asphalt or mineral pitches in oil or petroleum. It is used for painting ironwork under water parts of structures. Cellulose paint- nitro-cotton, celluloid sheets added to paint. Cellulose paint hardens by evaporation of thinning agent. It thus hardens quickly.  Nano application of paints Intumescent paint - The term intumescent describes the property of swelling. Base is nano silica. A thin film intumescent (TFI) coating is 0.25 to 5.0 mm. L Dry film thickness swells on hydration under the conditions of heat E and temperature T associated with the outbreak of fire, thus preventing spread of the fire. Gives four hour fire resistance. N P Thermo S – Microscopic ceramic balls suspended in rubber or ethyl cellulose. Provides thermal insulation of surfaces – walls, pipes, tanks Mend MW – self-healing coating Microscopic polyurethane dispersion with low VOC. Leads to gap closing and crack sealing.  EL PT N  EL P Building Materials and Composites T N Dr. Sumana Gupta Department of Architecture & Regional Planning, IIT Kharagpur Module 08 : Paints and Plastics Lecture 04 : Plastics CONCEPTS COVERED EL T What are plastics P Thermoplasts and thermosets N Characteristics of plastics Constituents of plastic Glass Fibre Reinforced Plastic (GFRP) and Glass Fibre Reinforced Concrete (GFRC) used in Zaha Hadid’s Heydar Aliyev Cultural Centre in Baku EL P T N Picture From Wikipedia Use in building’s external part Facade panels: examples- sandwich panels with PVC, plasticized plates and polyurethane foam and sandwich panels with enamelled iron covering and polyurethane foam core EL P T N Beijing Aquatic Centre Picture from Wikipedia Expanded polystyrene EL P T NFoamed plastic for thermal insulation  Wall lining and ceiling: Plastic panel EL T Laminates – blinds of window P Polypropylene sheet Shower curtain N Plastic Flooring (Vinyl) - lamina Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com  What are plastics Plastics is the generic name for polymers having high molecular weight Monomers chemically combine through polymerization to form polymers Generally derived from crude oil, petroleum and cellulose derivatives L Synthetic material made from a wide range of organic polymers E Like polyethylene, Poly Vinyl Chloride, nylon T Natural from plants (cellulose, latex) and animals (formaldehyde) P Mostly impervious in nature except the cellulose plastics N Non biodegradable hence hazardous Malleable and can be moulded into any desired shape and extensively used as building material It has low specific gravity of 1.3 to 1.4  Different Monomers L Polyethylene (PE) E Polyvinyl chloride (PVC) T Polytetrafluoroethylene (PTFE) P Polypropylene (PP) N Polystyrene (PS) Polymethyl Methacrylate (PMMA)  Thermoplastics Long molecular chain organic compounds On heating it melts and is mouldable Bond does not dissociate L Properties are retained E Can be recycled many times by heating T Similar to metals Dissolves in certain solvents P Swells in certain solvents N High strength – T/S of 28N/mm2 Bendable, takes impact Thermoplasts  Thermosets Cross links On heating the cross links break Irreversible chemical reaction L Can be moulded but becomes rigid at a certain temperature (127 – 1770C) E Loses of original properties on further heating T Chemically resistant P Heat resistant but gets charred at 3500C N High tensile strength – 40-45 N/mm2 Thermosets Long molecular chain organic compounds with cross links  Comparison Thermoplastics Thermosetting Plastics They change their shape upon Once formed they do not undergo shape heating and cooling, Low conversion upon heating and cooling. L melting point 500C High melting point 1770C E Expensive Cheap compared to thermoplasts Recyclable Not recyclable T The best example is polythene The best example is Bakelite which once P which changes its shape upon formed does not change its shape upon heating and cooling further heating N Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com  Characteristics Plastics are sufficiently strong for taking general loading condition However long term loading leads to deformation. Gains tensile strength with fibrous reinforcement (70 N/mm2) It may fail without warning L Hence can be used as filler material or supporting material, membrane but not structural material E Being organic most plastics are susceptible to temperature and heat T Poly Vinyl Chloride, phenol formaldehyde, urea formaldehyde withstand fire due to different molecular structure P Plastics being impervious are waterproof but N Mostly affected by Ultra Violet radiation – makes it brittle due to long time exposure Indoor application preferred Plastics are resistant to acids, alkalis, chemicals It is corrosion proof Low in thermal expansion and thermal conductivity (like wood) Foamed plastic or expanded plastic used as thermal insulator  Workability Plastics can be drilled, sawn and screwed like wood Plastics can be riveted, welded, clamped like metals L Easy to fabricate E Fabrication processes: T Blowing, calendaring, Casting, Laminating, moulding P Light in weight N Low in maintenance cost Plastics are inert but hazardous when burns Produce toxic fumes when burns (Polystyrene contains Chloroflurocarbon) Flame Spread Index measures propensity to burn rapidly and spread flames Smoke Development Index measures concentration of smoke a material emits as it burns. Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com  Constituents Resins – binder Plasticizers – modifies plasticity, for different strength, flexibility and hardness L They are separate polymer chains and delays crystallization. Ex. Adipates, Phytalates E Fillers / Additives – inert materials (fibrous form, powdered form, laminated form) T can make fire retardant, UV protected P Pigments – imparts colour and act as filler (zinc oxide, barytes) Paraffin, graphite, wax N Lubricating agents – makes easy to demould Catalysts (optional) – helps in polymerization like ester in urea formaldehyde  EL P T N PVC sheet Polycarbonate sheet Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com  EL PT N  EL P Building Materials and Composites T N Dr. Sumana Gupta Department of Architecture & Regional Planning, IIT Kharagpur Module 08 : Paints and Plastics Lecture 05 : Plastics (continued) CONCEPTS COVERED EL T Different types of plastics and applications P Poly Vinyl Chlorides N Acrylics Fluoropolymers Polycarbonates Polystyrene and polyethylene  Types of plastics Thermoplasts Thermosets Elastomer Polythene (low Modulus of elasticity) High Density Polythene Phenolic resins Rubber L Low Density Polythene Polypropylene Epoxy resins Neoprene E Polybutylene Melamine EPDM T formaldehyde P Acrylic (PMMA) PVC Butyl rubber CPVC (Chlorinated PVC) Polyester resins Vinyls N UPVC (Unplasticised PVC) Urea formaldehyde Polyamides (Nylon) Polycarbonate PTFE – Polytetrafluroethylene Fluropolymer ETFE – Ethylene Tetrafluro ethyelene  EL T PVC sheet form N P Moulded form Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com Plastics have replaced Glass in sheet form applications L Plastics have replaced Galvanised Iron sheet corrugated form applications E Plastics have replaced metals in pipe form for sanitation and water supply services Reinforced Plastics have replaced metal when used in pultruded form for door window frame T Plastics have replaced wood in door/ window shutter applications P Plastics have replaced wood in indoor applications like furniture Plastics have replaced wood in electrical wiring applications (Plastic casings) N Plastics have replaced 10% of the sand in a concrete mix Polymer modified bitumen is one of the specially designed engineered bitumen  Poly Vinyl Chloride The Carbon Chlorine bond of PVC is hydrophobic - resists oxidation (anti - corrosive) and burning -unaffected by chemicals, organisms L -Low maintenance cost E Plasticizers like phytalates can make it soft like rubber T Used extensively in sheet form pipe form P Hospitals potable water N Chemical/ pathological laboratories sewer lines Computer laboratories rain water pipes General flooring electrical cables and conduits  Poly Vinyl Chloride Laminated plastic boards of PVC Thermoforming is a manufacturing process where a L plastic sheet is heated to a pliable forming E temperature, formed to a specific shape in a mould, and trimmed to create a usable product. T PVC fiber form P Plastic door window shutters used in wet areas N PVC fiber reinforcement for concrete reduce plastic shrinkage and temperature related cracking CPVC – withstand high temperature, high tensile strength, chemically resistant UPVC - Hard and rigid - boring pipes and electrical conduits Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com  Acrylic Poly Methyl Methacrylate (PMMA) - Perspex, Plexiglass L Resembles glass – Half the weight with 10 times strength than glass Transparent, can take any colour pigment E Brilliance T Less affected by UV rays of sun Life - 10 years Scratch resistant P Difficult to work Use N Replaces glass in high rise and public buildings Corrugated sheet as roofing material  Fluoropolymers Flurocarbons gain properties like strength, toughness and self-lubrication from the aggregate effect of Carbon fluorine bond or Carbon fluorine and hydrogen bond L Ethylene tetrafluroethylene (ETFE) high performance plastic, corrosion resistant and high tensile strength over wide temperature range Polytetrafluroethylene (PTFE) T E P PTFE is known to have the lowest coefficient of friction of any known solid material. N Low surface energy implying low strength of attraction of the substrate, Hydrophobic tough and inert to virtually all chemicals Thickness as low as - 0.005 - 0.020 mm Heat resistant – 2600C Pneumatic panels to cover the outside of the football stadium, Allianz Arena L Burj Al Arab - PTFE coated glass E fabric protects from UV radiation, temperature variation, sand storm , sandstorms and fire. P T N Use of ETFE sheets - Eden Project, UK PTFE glass fiber fabric roof Jawaharlal Nehru Stadium. Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com  Polycarbonates Strong, tough materials, and some grades are optically transparent. Easily worked, molded, and thermoformed. Light weight and can withstand low to high temperature L Very thin sheets up to 2mm 1. Very high impact strength 200 time of glass 2. Easier to fabricate than acrylic T E 1. Scratches easily 2. Has poor UV-resistance in its natural form than acrylics P 3. Superior clarity 3. Higher Cost N Ultraviolet filters - extruded into polycarbonate to reduce solar gain without blocking natural daylight Polycarbonate sheet Polycarbonate roofing Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com Thermocol or Polystyrene (PS) It is a synthetic aromatic (benzene derivative) polymer made from the monomer styrene L Expanded polystyrene (EPS) foams are 95-98% air E Used as building insulation materials Polyethylenes LDPE, MDPE and HDPE grades P T N Chemical resistance Flexible and Tough UV resistant Uses: Water tanks, Pipe fittings, joints Source: pixabay.com, pexels.com, unsplash.com, wikimedia.org , stockvault.com, pikwizard.com Polymers in paints – Poly vinyl Acetate, Ethylene Vinyl Acetate in solvent Helps in film forming in plastic emulsion paints Polymers in adhesives – thermosets like urea formaldehyde, phenol formaldehyde, L Ethylene Vinyl Acetate in hot adhesives Fibre-reinforced plastic (FRP) is a composite made of a polymer matrix reinforced with fibers. The fibers are T E P usually glass or carbon in epoxy, vinyl ester, or polyester thermosetting plastic. N Fiberglass reinforced plastic Elastomers Neoprene exhibits good chemical stable and flexible over a wide temperature range Example: Gaskets for water sealing, thermal sealing Silicones are used in sealants, adhesives  Conclusion No end to building materials Context, climate, affordability of client, type of building, life of building L Reliable materials – Follow codes and specifications while recommending Availability of material and Skill T E P Ease of working with material during construction like joinery N Modular materials in use – fast construction, design limitations Research is on for advancements in the subject and applications  EL PT N